fix shapes.Plane.normal in #1159

marcomusy · Jul 23, 2024 · 7b4e124 · 7b4e124
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diff --git a/docs/changes.md b/docs/changes.md
@@ -5,13 +5,16 @@
 - fix Volume masking in #1146 by @ivishalanand 
 - fix `LegendBox` in #1153 by @GerritFischer
 - add `mesh.laplacian_diffusion()`
-- fix DistanceTool in #1158
+- fix `DistanceTool` in #1158
+- fix `shapes.Plane.normal` in #1159 by @smoothumut
+
 
 
 
 ## Soft-breaking Changes
 Changes that will break existing code whose fixing is trivial:
 
+- None
 
 
 ## Hard-breaking Changes

diff --git a/vedo/shapes.py b/vedo/shapes.py
@@ -3041,11 +3041,24 @@ def clone(self, deep=True) -> "Plane":
     @property
     def normal(self) -> np.ndarray:
         pts = self.vertices
-        AB = pts[1] - pts[0]
-        AC = pts[2] - pts[0]
+        # this is necessary because plane can have high resolution
+        # p0, p1 = pts[0], pts[1]
+        # AB = p1 - p0
+        # AB /= np.linalg.norm(AB)
+        # for pt in pts[2:]:
+        #     AC = pt - p0
+        #     AC /= np.linalg.norm(AC)
+        #     cosine_angle = np.dot(AB, AC)
+        #     if abs(cosine_angle) < 0.99:
+        #         normal = np.cross(AB, AC)
+        #         return normal / np.linalg.norm(normal)
+        p0, p1, p2 = pts[0], pts[1], pts[int(len(pts)/2 +0.5)]
+        AB = p1 - p0
+        AB /= np.linalg.norm(AB)
+        AC = p2 - p0
+        AC /= np.linalg.norm(AC)
         normal = np.cross(AB, AC)
-        normal = normal / np.linalg.norm(normal)
-        return normal
+        return normal / np.linalg.norm(normal)
 
     @property
     def center(self) -> np.ndarray: